Shockproof mechanical comparator



H. M. E. PASQUET SHOCKPROOF MECHANICAL COMPARATOR May 2', 1950 Filed Oct. 22, 1945 In I Q m INVENTUR I 2 Sheets-sheaf. 1

y 1950 H. M. E. PASQUET 2,506,167

SHOCKPROOF MECHANICAL COMPARATOR Filed 00?,- 22, 1946 2 Sheets-Sheet 2 INVENTUR BY I ATTORNEY Patented May 2, 1950 SHOCKPROOF MECHANICAL COMPARATOR Henri Marcel Edmond Pasquet, Neuilly-sur-Seine,

France, assignor to Societe dApplications Generales dElectricite et de Mecanique (S. A. G. E. M.), Paris, France, a society of France Application October 22, 1946, Serial No. 704,980 In France January 14, 1946 1 Claim.

The present invention relates to mechanical comparators of the kind including a contact member adapted to bear against the piece to be checked or measured, and means for amplifying the displacements of said contact member.

The chief object of my invention is to provide an apparatus of this type which is better adapted to meet the requirements of practice than those used for the same purpose up to the present time.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is a diagrammatic perspective view of an embodiment of a comparator according to my invention;

Fig. 2 is a similar view of another embodiment;

Fig. 3 is a view, also in perspective, of still another embodiment;

Figs. 4 and 5 are elevational views showing detail modifications;

Fig. 6 is a part view illustrating a modification.

As illustrated by Fig. 1, the apparatus according to my invention includes a supporting plate I and a contact member or rod 2 slidable in two fixed guides 3 and 4 carried by said plate. Rod 2 is screwed in a sliding sleeve 5 to which it may be secured in the desired relative position through any suitable means, not visible on the drawing. This sliding sleeve 5 is provided with means for preventin rotation thereof. In the embodiment shown by the drawings, said means consist in a projection 8 fitting with a sliding fit in a slideway I carried by plate I so as to guide said projection in a direction parallel to the axis of rod 2. A spring 5a fixed at one end to sleeve 5 constantly urges rod 2 toward the piece to be checked or measured. The movement of sleeve 5 in this direction is limited by an abutment 8 with which one 01' the end faces of said sleeve cooperates.

The other end face of sleeve 5 acts upon a finger 9a rigid with a first lever B pivoted at I!) on a fixed support. Contact between finger 9a and sleeve 5 is ensured by a spring ll. At its free end, lever 9 is provided with another finger l2 also kept by spring II in permanent contact with one end 01' a second lever l3. This second mentioned lever is pivoted at M on a fixed support. It is subjected to the action of a spring IS. The free end of lever l3 forms an index movable along a sector-shaped scale l6.

In the embodiment illustrated by the drawing, this last mentioned end oi. lever i3 is bent at right angles and its transverse portion also forms an index movable along a cylindrical scale I! concentric with sector IS. The indications supplied by the apparatus can therefore be read either on one scale or on the other. The end of lever l3 might be further bent at right angles so as to form another index cooperating with a scale parallel to I6 but visible from the other side of the apparatus.

The movements of lever l3 are limited in both directions by abutments l8, I9 adapted to cooperate with a finger 20 of said lever, near the pivot axis thereof.

According to my invention, the connection between sliding member 5 and lever 9 is cut off when the displacements of lever l3 are such as to exceed the possibilities of the apparatus.

For this purpose, finger 9a escapes to sliding member 5 when lever 9 is brought into the position that corresponds to the maximum angular displacement of lever [3. This result is obtained,

- in the example shown by the drawing, by the provision of a longitudinal notch 2| in member 5. Under normal conditions, that is to say as lon as the amplitude of the angular displacements of lever I3 is below the limit value, finger 9a is close to the edge of this notch 2|. When this amplitude reaches the limit value in question, finger 9a drops into notch 2| and the displacements of rod 2 cease to be transmitted to lever l3.

When rod 2 is not secured to sliding member 5, if the end of said rod is not in contact with a surface, the sliding member comes to rest on abutment 8. By turning rod 2 about its axis it is screwed or unscrewed and therefore moved in the axial direction.

When the apparatus support I is held in fixed position and rod 2 is in contact with a given surface, if said rod is rotated about its axis, while keeping its end in contact with said surface, this rotation produces a longitudinal displacement of sliding member 5, and consequently of finger 9a and an angular displacement of lever l3. It is thus possible to bring the index initially on any desired division of the scale, for instance zero, for a series of measurements.

When rod 2 is then secured with respect .to member 5, any longitudinal displacement of said rod causes corresponding displacements of finger 9a, lever 9 and lever 13, the free end of which moves along scales l6 and IT. The displacements of finger 9a, which are equal to the lengths to be measured. are thus multiplied in a ratio equal to the product of the respective lever arm ratios of levers 9 and I3.

Instead of being placed in a position perpendicular to the axis of contact member 2, the amplifying means may as well be disposed parallel to this axis as shown by Fig. 2.

For practical purposes, the apparatus preferably is made in the form of a circular fiat casing 22 as shown by Fig. 3.

Generally, the apparatus is adapted to be fixed in position by an extension of guide 4 which projects from the casing. However, in some cases, it may be advantageous to hold it by means of another part, rigid with one face of the casing or with the rear edge thereof.

Examples of such parts are given by Figs. 4 and 5, at 23 and 24, respectively.

The result obtained by the provision of a notch in sleeve 5 might also be obtained by means of a mere boss on said member.

The transmission to the index may be ensured through any suitable means, the use of two levers in series having been shown, in the above described embodiments, merely by way of example. For instance, .in the modification shown by Fig. 6, the end of lever 9 constitutes a toothed sector 9a in mesh with a pinion 39.journa1led on an arm 31 pivoted at 32 and subjected to the action of a spring 33 so as to keep pinion 30 constantly applied on toothed sector 9a. to the axis of pinion 30.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eflicient embodiments of my invention, it should "be well understood that I do not wish to be The index 34 is fixed K '4 limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claim.

What I claim is:

A mechanical comparator which comprises, in combination, a support, a contact rod adapted to bear against the piece to be measured, guided axially with respect to said support, a cylindrical sleeve screwed on said rod, means for preventing rotation of said sleeve with respect to said rod, means including a lever pivoted to said support for amplifying the displacements of said rod, a finger rigid with said lever adapted to bear against one edge of said sleeve for transmitting the displacements of said sleeve to said lever, said sleeve being provided with a longitudinal notch for engagement thereinto of said finger when the displacements of said rod exceed a given value.

HENRI MARCEL EDMOND PASQUET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 526,105 Hollister Sept. 18, 1894 526,960 Bath Oct. 2, 1 894 944,404 Bancroft Dec. 28, 1909 1,279,703 James Sept. 24, 1918 1,639,321 Wheelock Aug. 16, 1927 1,725,898 Chaperlo et al. Aug. 27, 1929 1,768,931 Pratt July 1, 1930 1,860,993 Clarkson May 31, 1932 

